Apparatus and method for determining position of capturing object using image including capturing object

Abstract

An image processing circuit captures an image of an capturing object and obtain an image of the capturing object, detects brightness in each criteria region in the image, computes a difference in the brightness of two adjacent criteria regions, determines a position of the capturing object in the image corresponding to a pixel having a brightness greater than a predetermined value on a basis of the difference in the brightness.

What is claimed is: 
     
         1 . An image processing circuit comprising:
 an image capture unit configured to capture an image of a capturing object and obtain an image of the capturing object;   a brightness detection unit configured to detect brightness in each criteria region in the image obtained by the image capture unit;   a computation unit configured to compute a difference in the brightness of two adjacent criteria regions detected by the brightness detection unit; and   a position determination unit configured to determine a position of the capturing object in the image corresponding to a pixel having a brightness greater than a predetermined value on a basis of the difference in the brightness computed by the computation unit.   
     
     
         2 . The image processing circuit according to  claim 1 , wherein
 the criteria region is one pixel in the image.   
     
     
         3 . The image processing circuit according to  claim 1 , wherein
 the image capture unit includes an image sensor configured to capture the image, and   the brightness detection unit, when detecting the brightness, reads the criteria region in order in a read out direction of the image from the image sensor.   
     
     
         4 . The image processing circuit according to  claim 3 , wherein
 the computation unit computes the difference in the brightness by subtracting a brightness of a second criteria region, of the two adjacent criteria regions, located behind in a reading direction of the brightness detection unit from a brightness of a first criteria region, of the two adjacent criteria regions, located in front in the reading direction.   
     
     
         5 . The image processing circuit according to  claim 4 , further comprising:
 a storage unit configured to store a position of a preceding pixel, the preceding pixel being the first criteria region where the difference in the brightness switches from 0 or greater to a negative value, wherein   the storage unit stores, as a top candidate with the brightness at a maximum, a position of the preceding pixel in a case where a distance from a first pixel to a second pixel is greater than a specified value, the first pixel being the criteria region where the difference in the brightness switches from a negative value to 0 or greater before the preceding pixel, and the second pixel being the criteria region where the difference in the brightness switches from a negative value to 0 or greater after the preceding pixel.   
     
     
         6 . The image processing circuit according to  claim 5 , wherein
 the position determination unit determines an actual position of the capturing object on a basis of the top candidate.   
     
     
         7 . The image processing circuit according to  claim 5 , wherein
 in a case where two top candidates obtained at different timing are temporarily stored and positions of the two top candidates are in a predetermined range, the storage unit stores, of the two top candidates, the top candidate with the higher brightness and deletes the top candidate with the lower brightness.   
     
     
         8 . The image processing circuit according to  claim 5 , wherein
 in the image, a search region surveyed for the preceding pixel can be set.   
     
     
         9 . The image processing circuit according to  claim 5 , wherein
 the storage unit stores the brightness of the first pixel and the brightness of the second pixel, the brightness of the first pixel and the brightness of the second pixel being used as a condition for the top candidate.   
     
     
         10 . The image processing circuit according to  claim 1 , further comprising:
 a storage unit configured to store a plurality of criteria regions in order, wherein   while the storage unit is storing the plurality of criteria regions in order, detection of the brightness by the brightness detection unit, computation of the difference in the brightness by the computation unit, and determination of an actual position of the capturing object by the position determination unit are executed in order.   
     
     
         11 . The image processing circuit according to  claim 1 , further comprising:
 a field programmable gate array (FPGA); and   a central processing unit (CPU) communicatively connected to the FPGA, wherein   the FPGA includes at least one of the brightness detection unit, the computation unit, and the position determination unit.   
     
     
         12 . The image processing circuit according to  claim 1 , wherein
 the image processing circuit is installed in an image capture apparatus.   
     
     
         13 . The image processing circuit according to  claim 1 , wherein
 the capturing object is a star,   the image processing circuit is a star tracker installed in a spacecraft, and   an attitude determining unit configured to determine an attitude of the spacecraft on a basis of a position of the star determined by the position determination unit is further provided.   
     
     
         14 . A method for determining a position of a capturing object comprising:
 capturing an image of the capturing object and obtaining an image of the capturing object;   detecting brightness in each criteria region in the image obtained by the capturing;   computing a difference in the brightness of two adjacent criteria regions detected by the detecting; and   determining an actual position of the capturing object on a basis of the difference in the brightness computed in the computing.   
     
     
         15 . A non-transitory computer-readable storage medium storing a program, the program causing a computer to execute:
 capturing an image of a capturing object and obtaining an image of the capturing object;   detecting brightness in each criteria region in the image obtained by the capturing;   computing a difference in the brightness of two adjacent criteria regions detected by the detecting; and   determining an actual position of the capturing object on a basis of the difference in the brightness computed in the computing.   
     
     
         16 . An image processing apparatus comprising:
 an image sensor configured to capture an image of a capturing object and obtain an image of the capturing object; and   at least one processor configured to execute a plurality of image processing on the image, wherein the plurality of image processing includes   detecting brightness in each criteria region in the image obtained by the image sensor,   computing a difference in the brightness of two adjacent criteria regions detected by the detecting, and   determining a position of the capturing object in the image corresponding to a pixel having a brightness greater than a predetermined value on a basis of the difference in the brightness computed by the computing.